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Sheet feeding device and image forming apparatus

a technology of image forming apparatus and feeding device, which is applied in the direction of thin material processing, article separation, transportation and packaging, etc., can solve the problems of high difficulty in preparing data tables corresponding to each type of sheets or automatically detecting all paper types, and achieving high precision

Inactive Publication Date: 2013-02-26
CANON KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is about a device for feeding sheets of paper. The device can detect the size, type, and number of sheets that are stacked on a tray, and adjust the pressure force accordingly. This ensures that the sheets are always pressed against the feeding mechanism with high precision, regardless of changes in the size or weight of the sheets. This feature helps to improve the quality and efficiency of the sheet feeding process.

Problems solved by technology

This is because high paper feeding pressure may easily cause multi-page feeding in which two or more sheets are fed at a time and low paper feeding pressure may easily cause defective feeding in which sheets are not successfully fed.
However, in a currently-used image forming apparatus in which various types of sheets are used, it is significantly difficult to prepare data tables corresponding to each type of the sheets or to automatically detect all the paper types.
That is, a design in which a user inputs the type of sheet to adjust pressure force as described in Japanese Patent Laid-Open No. 2006-56685, it is necessary to correctly input the sheet density and thickness: such an operation is complicated to the user.
In addition, determining pressure force correctly and appropriately requires huge amount of data which have been obtained experimentally.

Method used

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  • Sheet feeding device and image forming apparatus
  • Sheet feeding device and image forming apparatus
  • Sheet feeding device and image forming apparatus

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0035]FIGS. 2A to 2E schematically illustrate a configuration of a sheet feeding device according to a first embodiment. As illustrated in FIGS. 2A to 2E, in the sheet feeding device, a tray 51 carrying a stack of sheets S is supported rotatably about an axis of rotation 56 in a box-shaped paper cassette 55 and is capable of being raised and lowered. The tray 51 is provided with a paper sheet feed roller 54 and a separation roller 33. The paper sheet feed roller 54 is a sheet feeding device which catches and feeds the topmost sheet of the sheet stack on the tray 51. The separation roller 33 is pressed against the paper sheet feed roller 54. The sheets are conveyed one by one between the paper sheet feed roller 54 and the separation roller 33. The tray 51 is further provided with a pressure arm 57 which raises or lowers the tray 51 to let a surface of the topmost sheet of the sheet stack on the tray 51 be pressed against the paper sheet feed roller 54. A pressurizing unit which is a ...

second embodiment

[0058]A sheet feeding device according to a second embodiment will be illustrated in FIG. 6A in a schematic sectional view. In the first embodiment, the spring 58 is pulled by the lift motor 59 and thereby the tray 51 is rotated and the sheet S comes in contact with the paper sheet feed roller 54; in the second embodiment, the tray 51 is moved in a vertical direction to bring the sheet S into contact with the paper sheet feed roller 54.

[0059]For this purpose, an encoder 62 which reads an amount of rotation of the lift motor 59, and a paper sheet detection sensor 63 which reads a paper sheet S immediately before the sheet S comes in contact with the paper sheet feed roller 54 (FIG. 6B) are provided in the present embodiment similarly to the first embodiment. In contrast to the first embodiment, a lever 66 which moves upward together with the raising of the tray 51 is provided in the tray 51 in place of the pressurizer arm 57 in the present embodiment. In addition, a height of stacked...

third embodiment

[0061]FIG. 7 illustrates, in a schematic sectional view, a sheet feeding device according to a third embodiment. The third embodiment differs from the first embodiment in that a weight detection sensor 68, such as a strain gauge, is attached to the paper cassette 55. In the first embodiment, the initial total weight W of the sheets is calculated by a combination of the rheostat 61, the encoder 62 and the paper sheet detection sensor 63; in the present embodiment, the initial total weight W of the sheets is detected directly. At the time immediately after the user places a sheet, the tray 51 is supported by an axis of rotation 56 and the weight detection sensor 68. That is, the initial total weight W of the sheets can be detected directly on the basis of the output of the weight detection sensor 68 at this time.

[0062]Control to keep the paper feeding pressure before sheet feeding is started constant regardless of sheet size, sheet type and the amount of stacked sheets is the same as ...

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PUM

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Abstract

A sheet feeding device may include a tray, a sheet feeder, a pressurizing unit, a height detection unit, a weight detection unit, and a control unit. The tray may be raised and lowered. The sheet feeder sends out a sheet stacked on the tray. The pressurizing unit urges the tray to pressurize the sheet stacked on the tray against the sheet feeder. The control unit adjust pressure force of the pressurizing unit per change in height of sheets stacked on the tray on a basis of weight per unit height of the sheets, calculated on a basis of an initial total weight of the sheets stacked on the tray detected by the weight detection unit before a feeding operation is started and on a basis of the initial height of sheets stacked on the tray detected by the height detection unit before a sheet feeding operation is started.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a sheet feeding device which feeds a sheet from a sheet stack and to an image forming apparatus in which the sheet feeding device is incorporated.[0003]2. Description of the Related Art[0004]A related art image forming apparatus, such as a printer and a copier, is provided with a sheet feeding device which separates stacked sheets one by one and feeds the sheets to an image forming unit. The most common sheet feeding device feeds a sheet in the following manner: a tray carrying a stack of sheets is raised by a pressurizing unit, such as a spring, a sheet is pressed against a paper sheet feed roller, and the paper sheet feed roller is rotated to send the sheet out.[0005]FIG. 8 illustrates an example of a related art sheet feeding device provided with, in a paper cassette 55, a tray 51 which is rotatable about an axis of rotation 56. Sheets S are stacked on the tray 51. The tray 51 is rais...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): B65H1/18
CPCB65H1/14B65H2511/152B65H2515/10B65H2515/112B65H2515/34B65H2801/06B65H2220/01B65H2220/04B65H2220/02B65H2220/11B65H2511/15
Inventor CHIBA, YOSHINAO
Owner CANON KK